Shares of Versant Media Group, home to channels such as USA Network and CNBC, slumped more than 13% in its market debut after its spinoff from Comcast, underscoring investor skepticism around traditional TV businesses in the streaming era.Shares of Comcast rose about 1% on Monday.The spinoff is Comcast’s response to shifting market dynamics in the media industry, as streaming pressures traditional cable TV viewership, prompting media companies to rethink their ownership of legacy networks. 3 Versant house ...